Faculty Bibliography

Gout is a true crystal deposition arthropathy caused by the precipitation of monosodium urate into joints and periarticular soft tissues. It is the most common inflammatory arthropathy in men and women of older age with a male-to-female ratio of 3 to 8:1. The disease may progress from asymptomatic hyperuricemia through symptomatic acute gout attacks with asymptomatic periods into chronic symptomatic tophaceous gout. Although invasive arthrocentesis and demonstration of monosodium urate crystals on polarized light microscopy is definitive for the diagnosis of gout, dual-energy computed tomography (CT) allows for noninvasive visualization and reproducible volume quantification of monosodium urate crystals. Based on the high diagnostic performance, dual-energy CT has been included in the 2015 American College of Rheumatology/European League Against Rheumatism Collaborative Initiative Classification Criteria for Gout. Increasing evidence indicates the usefulness of dual-energy CT to guide the management of patients with suspected gout and monitor the effectiveness of urate-lowering medical therapy.

Interventional magnetic resonance (MR) neurography is a minimally invasive technique that affords targeting of small nerves in challenging areas of the human body for highly accurate nerve blocks and perineural injections. This cross-sectional technique uniquely combines high tissue contrast and high-spatial-resolution anatomic detail, which enables the precise identification and selective targeting of peripheral nerves, accurate needle guidance and navigation of the needle tip within the immediate vicinity of a nerve, as well as direct visualization of the injected drug for the assessment of appropriate drug distribution and documentation of the absence of spread to confounding nearby nerves.

Primary total knee arthroplasty is a highly effective treatment that relieves pain and improves joint function in a large percentage of patients. Despite an initially satisfactory surgical outcome, pain, dysfunction, and implant failure can occur over time. Identifying the etiology of complications is vital for appropriate management and proper timing of revision. Due to the increasing number of knee arthroplasties performed and decreasing patient age at implantation, there is a demand for accurate diagnosis to determine appropriate treatment of symptomatic joints following knee arthroplasty, and for monitoring of patients at risk. Magnetic resonance (MR) imaging allows for comprehensive imaging evaluation of the tissues surrounding knee arthroplasty implants with metallic components, including the polyethylene components. Optimized conventional and advanced pulse sequences can result in substantial metallic artifact reduction and afford improved visualization of bone, implant-tissue interfaces, and periprosthetic soft tissue for the diagnosis of arthroplasty-related complications. In this review article, we discuss strategies for MR imaging around knee arthroplasty implants and illustrate the imaging appearances of common modes of failure, including aseptic loosening, polyethylene wear-induced synovitis and osteolysis, periprosthetic joint infections, fracture, patellar clunk syndrome, recurrent hemarthrosis, arthrofibrosis, component malalignment, extensor mechanism injury, and instability. A systematic approach is provided for evaluation of MR imaging of knee implants. MR imaging with optimized conventional pulse sequences and advanced metal artifact reduction techniques can contribute important information for diagnosis, prognosis, risk stratification, and surgical planning.

Successful management of upper extremity arterial injury requires fast and accurate diagnosis. The rate of limb preservation depends on the location, severity, and time of ischemia. Indications for diagnostic imaging depend on the mechanism and type of injury, clinical signs, cardiovascular stability, and clinical suspicion. Because of ease of access, speed, and high accuracy for this diagnosis, multidetector computed tomographic (MDCT) angiography is often used as the first line imaging modality. MDCT systems with 64 slice configuration and more afford high temporal and spatial high-resolution, isotropic data acquisition and integration with whole-body trauma MDCT protocols. The use of individual injection timing protocols ensures high diagnostic image quality. Several strategies are available to reduce radiation exposure. Direct MDCT angiography findings of arterial injuries include active extravasation, luminal narrowing, lack of luminal contrast opacification, filling defect, arteriovenous fistula, and pseudoaneurysm. Important descriptors are location and length of defect, degree of luminal narrowing, and presence of distal arterial supply reconstitution. Proximal arterial injuries include the subclavian, axillary, and brachial arteries. Distal arterial injuries include the ulnar and radial arteries, as well as the palmar arterial arches. Concomitant venous injury, musculoskeletal injury, and nerve damage are common. In this exhibit, we outline the role of MDCT angiography in the diagnosis and management of upper extremity arterial injury, discuss strategies for MDCT angiography acquisition and concepts of data visualization, and illustrate various types of injuries.

PURPOSE/OBJECTIVE:To evaluate the feasibility of magnetic resonance imaging (MRI)-guided vertebroplasty at 1.5 Tesla using augmented reality image overlay navigation. MATERIALS AND METHODS/METHODS:Twenty-five unilateral vertebroplasties [5 of 25 (20%) thoracic, 20 of 25 (80%) lumbar] were prospectively planned in 5 human cadavers. A clinical 1.5-Teslan MRI system was used. An augmented reality image overlay navigation system and 3D Slicer visualization software were used for MRI display, planning, and needle navigation. Intermittent MRI was used to monitor placement of the MRI-compatible vertebroplasty needle. Cement injections (3 ml of polymethylmethacrylate) were performed outside the bore. The cement deposits were assessed on intermediate-weighted MR images. Outcome variables included type of vertebral body access, number of required intermittent MRI control steps, location of final needle tip position, cement deposit location, and vertebroplasty time. RESULTS:All planned procedures (25 of 25, 100%) were performed. Sixteen of 25 (64%) transpedicular and 9 of 25 (36%) parapedicular access routes were used. Six (range 3-9) MRI control steps were required for needle placement. No inadvertent punctures were visualized. Final needle tip position and cement location were adequate in all cases (25 of 25, 100%) with a target error of the final needle tip position of 6.1 ± 1.9 mm (range 0.3-8.7 mm) and a distance between the planned needle tip position and the center of the cement deposit of 4.3 mm (range 0.8-6.8 mm). Time requirement for one level was 16 (range 11-21) min. CONCLUSION/CONCLUSIONS:MRI-guided vertebroplasty using image overlay navigation is feasible allowing for accurate vertebral body access and cement deposition in cadaveric thoracic and lumbar vertebral bodies.

High-resolution multidetector computed tomography (MDCT) arthrography of the shoulder can diagnose internal derangement of the glenohumeral joints including abnormalities of the rotator cuff, glenoid labrum, and articular cartilage. Isotropic data sets and postprocessing techniques enable interactive three-dimensional image analysis that is capable of reducing artifacts for metal implants. In this article, we review the indications for MDCT arthrography of the shoulder, highlight techniques and important features of the MDCT acquisition, and review normal and abnormal MDCT arthrography appearances of the glenohumeral joint.

Hip arthroplasty has become the standard treatment for end-stage hip disease, allowing pain relief and restoration of mobility in large numbers of patients; however, pain after hip arthroplasty occurs in as many as 40% of cases, and despite improved longevity, all implants eventually fail with time. Owing to the increasing numbers of hip arthroplasty procedures performed, the demographic factors, and the metal-on-metal arthroplasty systems with their associated risk for the development of adverse local tissue reactions to metal products, there is a growing demand for an accurate diagnosis of symptoms related to hip arthroplasty implants and for a way to monitor patients at risk. Magnetic resonance (MR) imaging has evolved into a powerful diagnostic tool for the evaluation of hip arthroplasty implants. Optimized conventional pulse sequences and metal artifact reduction techniques afford improved depiction of bone, implant-tissue interfaces, and periprosthetic soft tissue for the diagnosis of arthroplasty-related complications. Strategies for MR imaging of hip arthroplasty implants are presented, as well as the imaging appearances of common causes of painful and dysfunctional hip arthroplasty systems, including stress reactions and fractures; bone resorption and aseptic loosening; polyethylene wear-induced synovitis and osteolysis; adverse local tissue reactions to metal products; infection; heterotopic ossification; tendinopathy; neuropathy; and periprosthetic neoplasms. A checklist is provided for systematic evaluation of MR images of hip arthroplasty implants. MR imaging with optimized conventional pulse sequences and metal artifact reduction techniques is a comprehensive imaging modality for the evaluation of the hip after arthroplasty, contributing important information for diagnosis, prognosis, risk stratification, and surgical planning.

BACKGROUND:Owing to the high risk of abscess drainage by craniotomy, imaging-guided stereotactic aspiration is considered an ideal choice in the management of brain abscesses. Interventional magnetic resonance imaging (MRI) represents a valuable technique for the treatment of brain abscess as a guiding modality. PURPOSE/OBJECTIVE:To evaluate the safety and efficacy of an interventional MRI system in performing the procedure. MATERIAL AND METHODS/METHODS:Thirteen brain abscesses in 11 patients were treated with percutaneous aspiration. All procedures were performed solely under the guidance of a 0.23-T open-configuration MRI scanner with optical tracking. Clinical and imaging follow-up was at 1 week, 1 month, 3 months, and 6 months. The changes of abscess, MRI features, and clinical symptoms were recorded. Procedure efficacy and safety were evaluated by success rate, procedure time, decrease of abscess, recovery rate, and complication. Descriptive statistical analysis was performed. RESULTS:MRI-guided stereotactic aspirations were performed successfully in 13/13 (100%) abscesses. The mean operating time was 70 min (range, 45-100 min). Follow-up MRI at 1 week after the procedure showed average reduction of abscesses by 60% (2.1/3.5). And the abscesses continued to get smaller by up to 89.7% (3.14/3.5) at 1-month follow-up. All cavities resolved at the end of the 6-month follow-up period. The recovery rate was 100% for fever, headache, vomiting, papilledema, meningismus, altered sensorium, 75% (3/4) for hemiparesis, and 83.3% (5/6) for epilepsy. There were no complications. CONCLUSION/CONCLUSIONS:Punctures of brain abscesses with subsequent aspiration can be performed safely and efficiently by monitoring the procedure using an open interventional MRI system.

Magnetic resonance (MR) neurography - guided nerve blocks and injections describe a techniques for selective percutaneous drug delivery, in which limited MR neurography and interventional MR imaging are used jointly to map and target specific pelvic nerves or muscles, navigate needles to the target, visualize the injected drug and detect spread to confounding structures. The procedures described, specifically include nerve blocks of the obturator nerve, lateral femoral cutaneous nerve, pudendal nerve, posterior femoral cutaneous nerve, sciatic nerve, ganglion impar, sacral spinal nerve, and injection into the piriformis muscle.

Imaging studies are central to the evaluation of persistent or recurrent symptoms after hip arthroplasty. The evaluation starts with radiographs and may be followed by arthrography, aspiration, scintigraphy, sonography, computed tomography, and MR imaging. Common etiologies of a painful or dysfunctional hip arthroplasty are mechanical loosening, polyethylene wear-induced osteolysis, adverse local tissue reaction to metal wear products, infection, fractures, heterotopic ossification, tendinopathy, and nerve injury. MR imaging with optimized protocols and dedicated techniques for metal artifact reduction is the most comprehensive imaging modality. In this article, we discuss and illustrate the imaging appearances of these conditions with a focus on the MR imaging evaluation.